Recently, mirror displays have been proposed for applications such as digital signage (e.g. Patent Literatures 1 to 4). A mirror display includes a mirror film provided on the viewing surface side of a display device so that the display device can function as a mirror. The mirror display provides images owing to display light emitted from the display device and is also usable as a mirror by reflecting external light. Known examples of a mirror layer include optical members with reflecting function such as reflective polarizing layers (e.g. Patent Literature 5), dielectric multilayer films (e.g. Patent Literature 6), and vapor-deposited metal films.
In such a mirror display, for example, if a mirror film (e.g. a reflective polarizing layer) alone is disposed on the viewing surface side of the liquid crystal display device, the mirror film may deflect to cause degradation such as distortion of a mirror image (reflected image) of the mirror. In order to prevent this problem, a configuration including a mirror film that includes an adhesive layer (e.g. Patent Literatures 7 to 9) in addition to the mirror layer has been employed in some cases, so that the mirror film attached to the substrate is used as a mirror plate. Meanwhile, in the cases where the substrate has an arithmetic average roughness of more than 0.04 μm on the surface to be attached to the mirror film (on the adhesive layer side), streaks observed to the naked eye have been reported due to the smoothness (irregularities) of the substrate (e.g. Patent Literature 10). Also, a method for preventing scratches on the mirror plate has been known, which is to dispose a hard coat layer (e.g. Patent Literature 11) on the surface opposite to the adhesive layer side of the mirror film as needed.